Need help with my dad's engine!

This isn't a mopar issue but my dad has a 68 mustang with a 302 in it. He is running a full msd ignition with a 6al box, bullit distributor and msd coil. At high rpm there is a loud popping noise that sounds a little like a back fire then it starts doing it at all rpm and cutting out bad. The distributor is also hot to the touch after running the engine. We replaced the distributor, coil, and took off the 6al and it still did it. I told him it could possibly be a fuel issue fouling out a plug so he is changing the carb tomorrow but I figured I would ask here tonight and try to get ahead of the ball. I'm not great with electronics btw. What are your thoughts though?